


Vol 90, No 3 (2017)
- Year: 2017
- Articles: 26
- URL: https://journal-vniispk.ru/1070-4272/issue/view/13366
Processes Using Various Catalyst Systems
Nature of influence exerted by Na2SiF6 on REE recovery from orthophosphoric acid solution in the course of CaSO4·0.5H2O crystallization
Abstract
Chemical and X-ray phase analyses were used to study the influence exerted by Na2SiF6 on the isomorphic inclusion of cerium into the structure of CaSO4∙0.5H2O precipitates formed from solutions of phosphoric acid hemihydrate (38 wt % P2O5). The poorly soluble suspensions of CaSO4∙0.5H2O precipitates can serve as adsorbents for cerium compounds, with CaSO4∙0.5H2O–NaCe(SO4)2∙H2O and CaSO4∙0.5H2O–CePO4∙0.5H2O solid solutions formed. The introduction of Na2SiF6 makes the sorption properties CaSO4∙0.5H2O several times better because the Na2SiF6 phase is a source of sodium cations and creates the necessary Na: Ce ratio of 1: 1 for extracting cerium from the liquid phase into a precipitate in the form of a CaSO4∙0.5H2O–[NaCe(SO4)2∙H2O + CePO4∙0.5H2O] solid solution. Under the industrial conditions in which extraction phosphoric acid is manufactured, a similar isomorphous capture of rare-earth elements of the cerium group (La–Sm) may occur in joint precipitation of CaSO4∙0.5H2O and Na2SiF6.



Interaction of organic acids with silicates in the course of joint mechanical activation
Abstract
IR spectroscopy, X-ray phase analysis, and high-resolution electron microscopy were used to examine the nature of the interaction of organic acids with silicates in their joint mechanical activation for the example of succinic acid. It was found that mechanocomposites with chemically bound components are formed in the course of activation of acid–layered silicate mixtures. It was shown that in the acid/nano-SiO2 composite, monomer molecules of the acid are bound to nano-SiO2 via molecules of adsorbed water, which form rather strong hydrogen bonds with the basic active centers of nano-SiO2 and hydroxy groups of the monomer molecules of the acid.



Chemical synthesis and granulometric composition of CaZr0.9Y0.1O3–δ powders
Abstract
CaZr0.9Y0.1O3–δ powders were synthesized by chemical solution methods: modified Pechini method and from solutions of inorganic salts in water and ethanol. The structure crystallizes into the orthorhombic type upon annealing at 1000°C for powders prepared by the Pechini method and from solution of salts in water. It was shown that CaZr0.9Y0.1O3–δ powders synthesized by various methods have different dispersities. The results obtained in a study of the granulometric composition by the sedimentation method and microscopic analysis enable fabrication of dense and mechanically strong electrolyte films and ceramics.



Behavior of aluminum in its anodic oxidation in aqueous solutions of acids and their salts
Abstract
Influence exerted by the nature and concentration of an electrolyte and by the electrolysis temperature on the process of anodic oxidation of aluminum in aqueous solutions was studied. It was shown that two modifications of aluminum hydroxide are formed as electrolysis products. Making higher the electrolyte concentration and raising the process temperature results in that the fraction of boehmite aluminum hydroxide in the product increases and that of bayerite aluminum hydroxide decreases. A scheme by which aluminum is anodically oxidized in aqueous solutions is suggested.



Synthesis, structure, and properties of substituted bismuth niobates Bi3Nb1–xErxO7–δ
Abstract
Results are reported of a study of the structural and electrical characteristics of substituted bismuth niobates with composition Bi3Nb1–xErxO7–δ, which are promising oxygen-ion conductors. The homogeneity regions of solid solutions were determined by X-ray phase analysis and electron microscopy with X-ray fluorescence microanalysis, and their crystal-chemical parameters were calculated. The electrical conductivity of sintered samples was examined by impedance spectroscopy.



Applied Electrochemistry and Metal Corrosion Protection
Structuring in the formation technology of electrode material based on nafion proton-conducting polymer and thermally expanded graphite containing platinum nanoparticles on carbon black
Abstract
Laboratory production technique is described for fabrication of an electrode material containing platinum nanoparticles on carbon black, proton-conducting polymer Nafion, and thermally expanded graphite for direct-energy-conversion systems (fuel cells, electrolyzers, electrochemical sensors). Results of a study of the material by differential thermal analysis are presented. Scanning and transmission electron microscopy was used to examine the structure of the material, and its elemental composition was determined by the EDX method. Dependences of the porosity of the material on its composition are presented.



Fabrication of multilayer ceramic structure for fuel cell based on La(Sr)Ga(Mg)O3–La(Sr)Fe(Ga)O3 cathode
Abstract
Fabrication by co-sintering method of a multilayer pore-free electrode–electrolyte structure promising for use in solid-oxide fuel cell and its characteristics have been studied. A material with high ionic conductivity of La0.88Sr0.12Ga0.82Mg0.18O3–δ (LSGM) served as electrolyte. The composite electrode was formed from a 1: 2 mixture of LSGM and LSFG (La0.7Sr0.3Fe0.95Ga0.05O3–δ). The maximum temperature of the materials co-sintering ability is 1250°C. It was shown by the impedance spectroscopy that the polarization resistance of the LSGM–LSFG electrode is 0.14 Ω cm2 at 800°C.



Effect of thermal treatment modes on ion-conducting properties of lithium-aluminum titanophosphate
Abstract
Dependence of the density of the Li1.3Al0.3Ti1.7(PO4)3 (LATP) ceramic on thermal treatment modes was studied. The conditions in which ceramic samples with density exceeding 90% are obtained were determined. It was found that the bulk ionic conductivity of LATP upon sintering at 1000°C for 2–6 h is (1.1–1.3) × 10–3 S cm–1 at 20°C, which corresponds to the maximum values for lithium-aluminum titanophosphate.



Spent zinc-plating electrolytes as secondary raw material for production of pigments
Abstract
Results are presented of a study of the precipitation of zinc from spent chlorammonium zinc-plating electrolytes with sodium phosphate. The zinc precipitation conditions were examined. The composition, structure, and properties of the resulting materials were studied and it was shown that the materials can be used as white pigments.



High-performance composite cathodes for Alkaline electrolysis of water
Abstract
A procedure for preparing and modifying composite electrode materials, allowing preparation of high-performance Ni-based catalysts for water electrolyzers with alkaline electrolyte, is reported. Electrodes for cathodic process, fabricated using this procedure, allow the power consumption for hydrogen production in alkaline water electrolyzers to be considerably reduced relative to known analogs used in Russia and other countries.



Sorption and Ion Exchange Processe
Sorption of arsenic onto inorganic sorbents modified with iron compounds
Abstract
Granulated inorganic sorbents based on silica gel of KSKG grade and aluminum oxide and modified with Fe(III) compounds were developed for water treatment to remove As(V). The influence of the particle size of the modifying additive on the ability of silica gel to take up As(V) was examined. The KSKG-based sorbents modified with nanoparticles of Fe(III) compounds exhibit the highest sorption capacity. The capacity of silica gel based sorbents modified with nanoparticles of iron compounds for As(V) is higher than that of analogous sorbents modified with iron oxides prepared by thermal decomposition of Fe(III) nitrate.



Macromolecular Compounds and Polymeric Materials
Development and study of elastomer heat-shielding materials containing zirconium dioxide
Abstract
The effect exerted by introduction of a combination of zirconium dioxide and thermally expanding graphite on the structure of the coke layer of an elastomer fireproofing and heat-shielding material based on ethylene–propylene rubber was studied. The presence of acute angles on the surface of a zirconium dioxide particle enhances its physicochemical activity in sorption (owing to excess surface energy) and promotes coking at high temperatures.



Heat-resistant network copolymers based on rolivsans modified with aromatic diamines
Abstract
Thermochemical transformations of rolivsans with aromatic diamines were studied by IR and NMR (1H, 13C) spectroscopy and by dynamic mechanical, thermal, and elemental analysis. The heat resistance of rolivsans is considerably enhanced by their modification with small additions (10 ± 5%) of an aromatic diamine with curing at 150–300 (320)°С.



Preparation of L-lactide of polymerization purity with removal of impurities by fractional melting
Abstract
Isolation and purification of L-lactide to reach the polymerization purity level with removal of impurities by fractional melting was studied. The process implementation was suggested, and the influence of various parameters on the rate and degree of impurity removal was examined. The optimum conditions for removal of the main impurities from L-lactide were found. The method allows preparation of L-lactide of polymerization purity in approximately 50% yield.



Effect of modifiers on properties and curing of aqueous emulsions of ED-20 epoxy resin in the presence of еpilink 701 cross-linking agent
Abstract
The dependence of the stability and structural-rheological properties of aqueous emulsions of an epoxy resin on the type and concentration of the modifier was examined. The working time, degree of curing, microstructure, and physicomechanical properties of polymer materials were studied in relation to the modifier type and its concentration in emulsions.



Effect of montmorillonite on polypropylene crystallization
Abstract
The effect of additions of pure and modified montmorrilonite on the polypropylene crystallization rate was studied within the framework of Avrami model. In the presence of these fillers in amounts of 2.5–5.0 wt %, both the crystallization rate and the degree of crystallinity increase, and at the content of these fillers increased to 10% and higher values these parameters decrease. Introduction of fillers enhances the mechanical properties of polypropylene, which allows the developed material to be recommended for the production of packaging film.



Pulp depitching in the bisulfite pulping step
Abstract
OS-20 nonionic surfactant produced in Russia was used as a depitching additive in bisulfite pulping. OS-20 ensures efficient depitching of bisulfite pulp produced from various kinds of wood (spruce, aspen, birch wood or their blends). The strongest decrease in the total and “harmful” pitch content in pulping in the presence of the surfactant was reached for spruce and aspen wood and for the blend of spruce and birch wood.



Various Technological Processes
Extraction of Cu2+ from aqueous solutions using microcapsules containing ionic liquid [BMIM]PF6
Abstract
Polysulfone (PSF) microcapsules filled with ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6] were successfully prepared via solvent evaporation method. The encapsulation capacity of 38.0% was achieved. Microcapsules showed a spherical, porous honeycomb structure. The size of microcapsules was approximately 110 μm and the thickness was approximately 10 μm. Microcapsules have excellent thermal stability, with a higher thermal degradation onset temperature of 360°C compared to traditional extractant-loaded microcapsules. Microcapsules were used to extract Cu2+ from aqueous solutions. The effect of chelator, pH, PSF, and ionic liquid on the extraction rate were studied. When chelator was added in aqueous solutions, and the pH of aqueous solutions was 4.5, the extraction rate of microcapsules reached the maximum value, which was 99.0%. These PSF microcapsules containing [BMIM][PF6] showed potential ability in the treatment of wastewater.



A kinetic study and application of electro-Fenton process for the remediation of aqueous environment containing toluene in a batch reactor
Abstract
In this work, the degradation and mineralization of toluene (TOL) in synthetic wastewater were studied by electro-Fenton process in a batch reactor. Also the impact of operational factors such as applied current, electrolysis time, concentration of TOL and Ferrous ion have been explored on the removal of toluene. In optimum conditions, the removal efficiency of TOL and total organic carbon (TOC) were 94.5 and 32.3% after 60 min of reaction. Based on the kinetic study the pseudo first-order rate constant for the removal of toluene and TOC was obtained at k = 5.90 × 10‒2 and 9.8 × 10‒3 min‒1, respectively.



Applicability of anthracite filtration‒micro electrolysis‒sand filtration for the treatment of surface waters containing high turbidity
Abstract
The effect of combined filtration efficiency on the performance of anthracite filtration‒micro electrolysis‒sand filtration (AMS) was investigated. Impact of different operating parameters, such as iron‒carbon ratio of micro electrolytic units, filtration velocity of AMS, were studied. It was found that when iron‒carbon ratio was 6: 4, the AMS’s average turbidity removal rate was 96.75% at the filtration velocity of 3 m h‒1. The results showed that when the filtration rate was 3‒9 m h‒1 and iron‒carbon ratio was 6: 4, the turbidity removal efficiency was over 94%, and the turbidity of the effluent was less than 1 NTU in effective filtration cycle. The effective filtration cycle can last for more than 5 h or longer. Meanwhile, the removal rate of UV254 was above 33%, and the concentration of iron ions in the effluent is less than 0.15 mg L‒1. Turbidity and iron indicators have reached the national drinking water standards. It was also found the mechanism of iron‒carbon micro electrolytic enhanced filtration by infrared spectroscopy and scanning electron microscopy. And It was also speculated the reasons for the reaction passivation.



Influence of chromate reducers on cement hydration
Abstract
Present research compared the effect of chromate reducers such as ferrous sulphate heptahydrate (FeSO4·7H2O) and stannous sulphate dihydrate (SnCl2·2H2O) on the hydration of cement paste, using water‒cement ratio of 0.5 and sealed in plastic bags without curing for 28 days. Uncured hydration properties of cement paste are investigated in detail by thermogravimetric analysis (TGA) and verified with the use of scanning electron microscopy (SEM) and X-ray powder diffractometry (XRD). This research concluded that the cement paste with 0.1% additives showed better hydration in the uncured condition than the control.



Effect of chemical modification and improvement of polyurethane formulation: Application of thermal insulation
Abstract
Polyurethane (PU) insulating materials and rigid PU foams (RPUFs) are of great importance for scientific and industrial research. These materials are used for a variety of other applications, such as buildings, institutions, pipes and appliances. In this sense, this study is aimed to optimize and improve the heat resistance of the polymer. It also has to improve the formulation and characterize aqueous polyurethane dispersions to enable their use and application in thermal insulation. The polyurethane was produced by the polyaddition catalytic reaction of a polyol (Pol) with diphenylmethane diisocyanate (MDI) in the presence of a foaming agent, cyclopentane (CP). To prepare aqueous polyurethane dispersions for a thermal insulation, which are stable in time and have homogeneous dispersive properties (chemical structure, density, viscosity), several dispersions were obtained with different Pol/MDI/CP ratios to reduce the demolding time. The formulation and its modifications are industrially applicable and satisfy environmental requirements.



Synthesis and rheological property of various modified nano-SiO2/AM/AA hyperbranched polymers for oil displacement
Abstract
In this study, various modified nano-SiO2 functional monomers (nano-SiO2-KH540-MAH) were prepared and reacted with acrylamide (AM) and acrylate (AA) to synthesize a water-soluble hyperbranched copolymer (nano-SiO2/AM/AA) for medium- and low-permeability reservoirs and heterogeneous reservoirs by using the redox free-radical polymerization strategy. The HCl‒CH3CH2OH titration expectedly demonstrated that the monomers underwent a controlled modification. The copolymers were characterized by a series of experiments, including IR, 1H NMR and DLS methods. Furthermore, it was shown that, compared with the rheological properties of various modified copolymers, Polymer-40 has a better viscosity and elasticity due to the better molecular structure. An indoor displacement test demonstrated that the mobility control ability and the EOR ability had a favorite relationship with rheology. The RF, RRF and EOR of Polymer-40 were higher than the same parameters of other modified copolymers.



Brief Communications
Electrodeposition of nickel-based composite coatings from a sulfamate electrolyte
Abstract
Nickel-based composite coatings modified with carbon nanotubes were electrodeposited from a sulfamate electrolyte. The functional properties (friction coefficient, protective power) of these coatings were compared to those of electrodeposited nickel coatings without dispersed phase. Incorporation of carbon nanotubes into nickel coatings leads to a 1.40–1.45-fold decrease in the sliding friction coefficient and to a 1.35–1.40-fold increase in the width of the passive potential range.



Synthesis of oxide materials in the Mg–Sn–O system for use in composite solid electrolytes
Abstract
Joint precipitation of tin(IV) and magnesium hydroxides from hydrochloric acid solutions was studied by differential thermal and X-ray diffraction analysis, low-temperature nitrogen adsorption, and electron microscopy. The characteristics of MgSn(OH)6 thermal decomposition products were determined. The results of measuring the ionic conductivity of MgSnO3–CsNO2 composites show that magnesium stannate is promising as a heterogeneous additive to composite solid electrolytes.



Erratum
Erratum to: “Effects of TiO2 on the hydrophilicity of сotton/polyester (50/50) blend fabric under UV irradiation”


